The present invention relates to a honeycomb structured body and a manufacturing method for the honeycomb structured body.
In recent years, environmental considerations have increased the necessity for removing particulate matter contained in exhaust gases of combustion apparatuses, such as an internal combustion engine and a boiler. In particular, regulations relating to removing of particulate matter (PM) including graphite particles discharged from diesel engines tend towards tightening in Europe, the United States, and Japan. A honeycomb structured body referred to as a diesel particulate filter (DPF) has been used to capture and remove matters such as PM. A honeycomb structured body is accommodated in a casing that is arranged on an exhaust passage for a combustion apparatus. The honeycomb structured body has a large number of cells that extend in the longitudinal direction of the structure. The cells are partitioned by partitions. In every pair of adjacent cells, one cell has an open end on one side and the other cell has an open end on the opposite side. The opens cells are sealed by plugs. The plugs are arranged in a lattice on each end surface (inlet side end surface and outlet side end surface) of the honeycomb structured body. Exhaust gas enters open cells at the inlet side end surface of the honeycomb structured body, flows through the porous partitions, and is discharged from adjacent open cells at the outlet side end surface. For example, PM discharged from a diesel engine is captured by the partitions that function as a filter, and accumulates on the partitions. The PM accumulating on the partitions is burned and removed by a heating means, such as a burner or a heater, or by the heat of the exhaust gas. In this specification, the burning and removing of PM is also referred to as “removing PM” or “regenerating the honeycomb structured body”.
Various honeycomb structured bodies have been known (refer for example to JP-A 2003-260322, JP-B 3121497, and JP-A 2005-154202). The honeycomb structured body described in JP-A 2003-260322 has a circular cross-section and includes reinforced portions arranged at predetermined positions of its outer wall. The predetermined positions on which the reinforced parts are arranged are outer wall positions having a low strength.
The honeycomb structured body described in JP-B 3121497 is formed by a plurality of honeycomb members that are divided by planes parallel to the axis of the honeycomb structured body. More specifically, the honeycomb structured body is formed by eight honeycomb members having rectangular pillar shapes and four honeycomb members having isosceles right triangular cross-sections. The cross-section of the honeycomb structured body is octagonal. A sealing material is interposed between adjacent honeycomb members to integrally bond the honeycomb members.
The honeycomb structured body described in JP-A 2005-154202 has a circular cross-section. This honeycomb structured body is obtained by combining a plurality of honeycomb members having rectangular pillar shapes into a bundle using a sealing material and partially cutting the bundle of the honeycomb members to adjust the outer shape of the bundle.
The entire contents of JP-A 2003-260322, JP-B 3121497, and JP-A 2005-154202 are incorporated herein by reference.